1. Field of the Invention
The present invention relates to a sustained release tablet containing indapamide and the process of manufacturing sustained release tablet containing indapamide, known medicinal product of diuretic activity administered in the therapy of primary hypertension.
2. Discussion of Background Information
From a specification of the patent No: EP 519820 it is known a sustained release matrix tablet of indapamide and a process of its manufacturing. Sustained release is controlled by the use of methylhydroxypropylcellulose and polyvidone, the percentages of which are from 30 to 50% and from 2 to 10%, respectively, of the total mass of the tablet. The percentages of the cellulose and polyvidone compounds permit the sustained release of indapamide in a manner that is linear for a period of at least eight hours and the release of 50% of the total quantity of indapamide within a period of from 5 to 14 hours. Additionally, the percentages of cellulose and polyvidone compounds permit the sustained release of indapamide to give blood levels in humans of from 20 to 80 ng/ml at most after administration of the tablet by the oral route. A process for the preparation of an indapamide matrix tablet known from the patent No. EP 519820 is based on that there are used both a moist granulation technique and a direct compression technique, comprising the steps as follows. First, indapamide, polyvidone and lactose are mixed, then moistened with an aqueous-alcoholic solution to yield a moist mass which is then granulated, dried and then graded so as to obtain a granulate whose physical characteristics allow good filling of the moulds of a rapid compression machine. The obtained granulate is mixed with methylhydoxypropylcellulose and lubricated with magnesium stearate and colloidal silica. The final step is compression of the lubricated mixture in a rotary compression machine, so as to obtain tablets having a hardness of approximately from 60 to 75 N.